In-line explosion arrester

ABSTRACT

This invention relates to a system for detecting an explosion in a pipeline carrying molten explosive material and halting the spread thereof by blocking the propagation of the detonating wave by a detonation arresting means that is electrically activated by an electronic switch which is sensitive to the initial detonation.

United States Patent 1 Jablansky [4 Dec. 25, 1973 IN-LINE EXPLOSIONARRESTER [75] Inventor: Louis Jablansky, Fair Lawn, NJ.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Dec. 12, 1972 [21] Appl. No.: 314,299

Related US. Application Data [62] Division of Ser. No. 139,337, May 3,1971, Pat. No.

[52'] US. Cl. 137/68, 285/3 [51] Int. Cl.. Fl6k 13/00 [58] Field ofSearch ..137/6771; 317/D1G. 8;

285/3, 4, l8, DIG. 21; 85/D1G. l

[56] References Cited UNITED STATES PATENTS 1,284,197 11/1918 Lamer etal. 137/68 2,399,843 5/1946 Adams 137/67 X 3,032,356 5/1962 Bot sford3,509,942 5/1970 Lindberg 137/67 X Primary ExaminerHenry T. KlinksiekAssistant ExaminerRichard Gerard Attorney-Edward J. Kelly [5 7 ABSTRACT1 Claim, 9 Drawing Figures I as 97 m3 /07 RATENTED DEC 2 5 i873 SHEET 3BF 7 WENIED DEC 2 5 I975 SHEET 3 [If 7 "ATENTED DEC 2 5 I975 sum 5 [1F 7PATENTED DEC 2 5 I975 SHEET E OF 7 PATENTED DEC 2 5 I975 SHEET 7 UF 7IN-LINE EXPLOSION ARRESTER This is a division, of application Ser. No.139,337, filed 3 May 1971 now US. Pat. No. 3,739,796.

BACKGROUND OF THE INVENTION The invention described herein may bemanufactured, used and licensed by or for the Government forgovernmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to a system forarresting detonations in a continuous process explosive pipe-line suchas those used in the manufacture of molten TNT and similar explosivematerials.

Prior art devices using explosive arresters were not capable of stoppinga detonation from propagation in a conduit containing molten explosivesuch as tri-nitrotoluene. Devices used in the past, have attempted'toarrest the propagation of an initial explosion in a line carrying theexplosive by controlling and limiting the diameter of the pipe and/or bythe insertion of loops in the production line. Both of these methodshave been found to be of limited merit. In manufacturing operations,where molten explosive is being transported from one processingoperation to another, limiting the conduit to a critical diameter whichwill inhibit the propagation will not permit adequate volume of materialto flow; likewise where loops of sufficient number are introduced intothe line to substantially inhibit propagation of a detonation theirresultant effect in restricting the volume of flow through the conduithas proved objectionable.

SUMMARY OF THE INVENTION The present invention is a system forinterrupting the propagation of a detonation wave in a conduit carryingexplosive material such as molten tri-nitro-toluene by attenuating theaforesaid wave to a minimum energy level, either upstream and/ordownstream from the explosion point, thereby rendering the initialexplosion ineffective in initiating and propagating further explosionsalong the line.

One of the objects of this invention is to provide quenching action inan explosive train in approximately one millisecond.

Another object of this invention is to provide an arresting device forquenching pipeline explosions which is suitable for more than one typeof explosive.

Another object of this invention is to provide a system for interruptingthe propagation of a detonation wave in a conduit containing a moltenexplosive which system does not restrict the normal material flowthrough the conduit.

Another object of this invention is to provide a means for interruptingthe detonation wave in an explosive carrying pipeline withoutsubstantially limiting the physical size or shape of the line.

Another object of this invention is to provide a simple, cheap andcompact means for effectively quenching an accidental explosion in anexplosive carrying pipeline.

For a better understanding of the present invention, together with otherand further objects thereof, reference is made to the followingdescription taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic and blockdiagram of an in-line explosion arrester, which closes a passageway whenactivated by an electronic sensing circuit and switch.

FIG. 2 is a modification of the schematic and block diagram shown inFIG. l,'showing a means for arresting a detonation by opening apassageway when the arresting means is activated by an electronicsensing circuit and switch.

FIG. 3 is an electrical schematic of the electronic switch circuit l6shown in FIGS. 1 and 2.

FIG. 4 is a cross-sectional view-ofthe in-line explosion arresterschematically illustrated in FIG. 1.

FIG. 5 is a sectional view of an in-line explosion arrester illustratedin FIG. 4, and taken along line 5-5.

FIG. 6 is a sectional view of aforementioned in-line explosion arresterillustrated in FIG. 4, and taken along line 66.

FIG. 7 is .a cross-sectional expanded, elevational, view of one of thetwo detonation arresting means schematically illustrated in FIG. 2.

FIG. 8 is a partial sectional and plan view of the detonation arrestingmeans of FIG. 7 taken along line 8-8.

FIG. 9 is a cross section of the detonation arresting means taken alongline 9--9 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2,a detonation sensor breakwire 10 is coiled about the longitudinalcircumference of the liquid explosive pipe-line 12 having a product flow14. The detonation breakwire sensor 10 is electrically connected to apair of input terminals 18 and 20 of an electronic switch circuit 16.Circuit 16 maintains an in-line explosion arresting means 26 in FIG. 1and two arresting means 28, 28 in FIG. 2 nonoperative so long as thebreakwire sensor is intact. When an explosion causes the breakwire 10 torupture anywhere along pipe-line 12 or 12, the electronic switch circuit16 will energize the detonation arresting means 26 and 28 throughdetonator leads 23 and 25 and to arresting means 28' through a parallelconnection at junctions 27 and 29. In the arrangement shown in FIG. 1the in-Iine explosion arresting means 26 prevents the propagation of theexplosive train by blocking the line. A barrier attenuates thedetonation wave to a minimum energy level rendering the wave incapableof further explosive propagation. In FIG. 2 the explosion arrestingmeans 28 and 28' cause the explosive sectional pipe-line 12' to separatefrom line 12 thereby opening up the explosive pipe-line 12 causing acritical discontinuity in the explosive fluid and thereby preventingpropagation of the explosion. In both arrangements described above thearresting means will interrupt the propagation of the detonating wave inapproximately 1 millisecond after rupture of the breakwire sensor.

FIG. 3 is an electrical schematic of the electronic switch 16illustrated in FIGS. 1 and 2. A power source 17 is connected through aswitch 19 and charging resistor 30 across the series combination siliconcontrolled rectifier 34 and electric detonator 52, also shown on FIGS. 4and 7. Electric detonator leads 23 and 25 are connected to the switch 16output terminals 22 and 24. A capacitor 35 is connected in parallel withthe series combination of the silicon controlled rectifier and electricdetonator 52 at junctions 42 and 21. A voltage dividing resistor 32 isconnected at one end to the common junction 42 between the limitingresistor 30, an anode lead 36 and capacitor 35, and the other end to thecommon junction 46 between the trigger electrode 40 and the electricalconnection 47. The other end of the electrical connection 47 isconnected to terminal 18. Junction 21 is also connected to terminal 20.The low resistance path of the breakwire sensor 10 when connected toterminals 18 and 20 keeps the trigger electrode 40 of silicon controlledrectifier 34 at a low potential and therefore in a cut-offnon-conducting condition. When the breakwire sensor 10 is broken thepotential at junction 46 is raised to a voltage approaching anodepotential causing the siliconcontrolled rectifier 34 to conduct therebydischarging the energy stored in capacitor 35 to the electric detonator52, and initiating the detonation arresting means 26, 28 and 28'.

FIG. 4 shows the details of an in-line explosion arrester 26 illustratedin FIG. 1. A threaded detonator holder and closure 48 has an axial bore51 which is filled with an insulating cement 50 which holds detonatorleads 23 and 25. A smaller axial bore 53 permits the passage of leads 23and 25 to a larger axial bore 55 which contains an electrical detonator52. The detonator holder 48 is coaxially threaded into a bushing 54which is in turn threaded into one end of the detonation trap housing60. A space 56 is provided between the threaded portion 49 of thedetonator holder 48 and an inner bore 57 of the threaded bushing 54.This inner space 56 permits gases generated by the detonator 52 toexpand, thereby minimizing any shock wave generated by detonator 52. Ahollow steel cylindrical plug 68 is operatively positioned below thethreaded bushing 54 and slidably engages the inner wall of thelongitudinal bore 61 of housing 60 at one end of its outer peripheralsurface. Steel plug 68 at said first end has a first annular O ringgroove 65 which contains a first ring 64 and a transverse bore on oneside of said first end for holding a shear pin 62. The shear pin 62 fitsin a shear pin housing groove 63 permitting the bottom surface 67 of thethreaded bushing 54 to mate with the bottom surface of the threadedhousing bore 69. Steel plug 68 has a first threaded bore 59 on an openend and a second smaller axially aligned bore 81 on a closed end. Asteel threaded insert 70 is threaded onto the first threaded steel plugbore 59 closing the second plug bore 81 and retaining therein a lowdensity polyurethane foam 72. The steel threaded insert 70 has a centralaxially aligned bore 79 and inserted therein is a compressible wafer 58oppositely disposed and in line with the electric detonator 52. Thepurpose of the compressible wafer 58 is to absorb some of the shockcaused by detonator 52. The purpose of the polyurethane foam 72 is tofurther attenuate the detonation wave and to prevent spalling of wall ofplug bore 81. The TEFLON sleeve transverse port member 66 retains theother smaller closed end of steel plug 68 in a cup shaped recess 66'therein and lines up the transverse bore 71 transverse bores 60' withhousing 60. A second annular O ring groove 65' is located in the bottomperipheral surface of the TEF LON sleeve 66 transverse to thelongitudinal axis 86 and adjacent to the transverse bore 71; a second 0ring 64' is located in the aforesaid second 0 ring groove 65. O ring 64'acts as a seal to prevent the molten explosive product from enteringinto the space between housing 60 and TEFLON sleeeve 66. A third annularO ring groove 65" is located transverse to the longitudinal axis 86 andadjacent to transverse bore 71 and has therewithin a third 0 ring 64"which acts as a seal to retain the molten explosive material within thetransverse bore 71 and the housing-60. An aluminum decelerating stop 76which is circular in cross section when viewed along line 6-6 isattached to the underneath side of the transverse bore wall 71' byscrews 84 and is slightly smaller in diameter than the inside diameterof the longitudinal central bore wall 61 of housing 60. Pipe flanges 74and 74 are circumferentially welded at 73, 73' to housing 60 so that theflange bore 75, 75' are axially aligned with the transverse bore 60.Fourth annular O ring grooves 65" and fourth 0 rings 64" are located inthe flange mating faces 77, 77' to form a seal with mating flanges (notshown) which are hermetically attached to pipe line 12 so that theexplosive molten material may be maintained therein. Housing 60 has athreaded boss 83 on its other end and to which a threaded tapered stop82 is screwed thereon. The wall of tapered bore 80, located adjacent toclearance space 78, gradually slows decelerating stop 76 which has beengiven motion by electrical detonator 52, effectinga closure oftransverse bores 60 with a minimum of shock impact thereby safelyattenuating the approaching detonating wave along pipe-line 12.

An initiating pulse from the electronic switch 16 through leads 23 and25 will activate electric detonator 52 causing gases to be generatedabove wafer 58; the pressure of these gases creates a force againststeel plug 68 causing shear pin 62 to shear and the TEFLON sleeve 66 tomove in a direction in line with longitudinal axis 86 closing thetransverse bores 60 and thereby attenuating any subsequent detonationwave from being propagated along explosive line 12.

In FIG. 5, a cross-sectional view taken along line 5-5 of FIG. 4, we seethe concentric arrangement of polyurethane foam 72, the retaining wallsof steel plug 68 surrounding the foam 72, and the TEFLON sleeve wall 66intermediate to the steel plug 68 and the surrounding housing 60.

F IG. 6 shows a cross-sectional view of the housing 60 and thedecelerating stop 76 when the detonation arresting means 26 is in itsopen state. Housing 60 is circumambient the decelerating stop 76 andseparated therefrom by clearance space 85. A plurality of screws 84, 84'holds the decelerating stop 76 affixed to the transverse bore wall 71'(not shown).

FIG. 7 shows, in partial cross-section, one of two identical detonationarresting means 28 and 28 which upon receipt of an intiating signal fromelectronic switch 16 will cause sectional pipeline 12' in FIG. 2 toseparate from pipe line 12. Upper flange 90 has an axial first centralbore 104 on its outer surface 91 and concentric therewith a secondcentral bore 106; pipeline 12 is positioned in the upper flange firstbore 104 and welded to the outer surface 91 at weld 99. In a similarmanner lower flange 92 has an outer surface 93 welded to sectionalpipeline 12 at weld 99'. Sectional pipe-line 12' is axially aligned withpipeline 12 by the lower flange first central bore 112 and a concentricsecond central bore of smaller diameter 108. The upper flange 90 isconnected to the lower flange 92 by a plurality of bolts 102, 102, 102"and 102" (see H65. 8 and 9) which pass through upper flange clearanceholes 105,

105, 105" and 105" into aligned holes 103, 103, 103" and 103". Acircular upper fuze ribbon channel 95 is positioned immediately adjacentto electric detonator hole 109 which holds the electric detonator 52. Amatching circular lower fuze ribbon channel 97 is positioned opposite tothe upper fuze ribbon channel 95 so that when both flanges are assembledtogether a closed annular channel is formed for containing thedetonating fuze ribbon 94 therein. A circularly shaped upper flangetongue 98, of smaller diameter than the fuze ribbon channels 95 and 97,mates with an annular channel 96 located in the lower flange 92. Anannular O ring channel 101 of smaller diameter than the upper flangetongue 98 is intermediate to a central bore 104 and the upper flangetongue 98 and located in the same flange face as the upper fuze ribbonchannel 95. An ring 100 is positioned within the O ring channel 101 andspace formed between channel 101 and lower flange inner surface 111. TheO ring 100 in contact with the inner surface 111 of the lower flange 92acts as an effective seal preventing the molten explosive in pipe line12 and sectional pipe line 12' from escaping or from contactingdetonating fuze ribbon 94 or the electrical detonator 52. A threadedhole 110 is opposite to and connected with electric detonator hole 109thereby permitting detonator holder 48 and electric detonator 52 to beoperatively positioned immediately adjacent to the detonating fuzeribbon 94.

FIG. 8 shows a plan and partial cross-section taken along line 88 ofFIG. 7 of the upper flange outer surface 91 with a plurality of screws102. 102, 102", 102" positioned between pipeline l2 and the outsidediameter of the upper flange 90.

FIG. 9 shows a view of the upper flange inner surface taken along line99, a cross-section of detonating fuze ribbon 94, electric detonator 52,detonator holder 48, and a plurality of screws 102, 102', 102" and 102"in clearance holes 105, 105, 105" and 105" respectively. This view showsthe concentric positions of the O ring 100, O ring groove 101 and thedetonating fuze ribbon 94 about the second central bore 106. Detonatorholder closure 48 and electric detonator hole 109 are axially in lineand radially positioned with respect to detonating ribbon 94 so that theelectric detonator 52, located in electric detonator hole 109, isadjacent to detonating ribbon 94.

An initiating pulse from the electronic switch 16 through leads 23 and25 and 23' and 25' in parallel connection at junctions 27 and 29, asshown in FIG. 2, will cause the electric detonator 52, as shown in FIG.9, in detonation arresting means 28 and 28' respectively to fire thedetonating fuze ribbon 94. The mild explosive force of detonatingribbons 94 and 94' (not shown) in arresting means 28' will cause thelower flange halves 92 and 92' (not shown) of detonating arresting means28 and 28 to simultaneously separate from the upper flange 90 and 90(not shown) causing line 12' to be opened, thereby preventing thepropagation of the detonation wave along pipe-line 12.

From the above description it will be evident that the inventionprovides a system for rapidly detecting an explosion in an explosivematerial carrying pipe-line and arresting the detonation wave therebypreventing further propagation of the explosion.

I wish it to be understood that I do not desire to be limited to theexact detail of construction shown and described for obviousmodification will occur to a person skilled in the art.

What is claimed is:

l. A system for detecting an initial explosion in a pipeline carryingexplosive materials and arresting said explosion prior to thepropagation of a detonation wave along said pipeline which comprises:

a breakwire sensor operatively positioned around said pipeline;

an electronic switch having a pair of inputterminals electricallyconnected to said breakwire for maintaining said electronic switchnon-operative when said breakwire is intact, an a pair of outputterminals for supplying a voltage pulse when said breakwire is broken,and which includes;

a power source;

a silicon controlled rectifier having an anode terminal connected to apositive terminal of said power source through a series connectedcharging resistor and switch, a trigger electrode connected to thecommon junction of a first terminal of said pair of input terminals andto one end of a voltage dividing resistor, said voltage dividingresistor having its other end connected to the common junction of saidcharging resistor and said anode terminal, a cathode terminal connectedto a first terminal of said pair of output terminals;

a load capacitor having one terminal connected to the common junction ofa second terminal of said pair of input terminals and a second terminalof said output pair of terminals and the negative side of said powersource, and a second terminal connected to the common junction of saidanode terminal, said voltage dividing resistor, and said chargingresistor,whereby said capacitor discharges its stored energy to saidpair of output terminals when said breakwire sensor is broken, causingsaid silicon rectifier trigger electrode to be more positively biased,triggeringsaid silicon rectifier; and

means for arresting a detonation disposed proximate said pipelineelectrically coupled to said pair of output terminals and responsive tosaid voltage pulse which includes;

an upper flange having a central counter-bore located on an outersurface of said flange to which said pipeline is welded, a secondsmaller central bore coaxial with said counter-bore and said pipelineconnecting to an inner surface of said upper flange, an annular O-ringgroove in said inner surface of larger diameter than said counter-boreand concentric thereto, an annular upper flange tongue larger indiameter than said O-ring groove, concentric therewith and protrudingfrom said inner surface, an upper fuze ribbon channel in said innersurface of larger diameter than said annular upper flange tongue andintermediate to said upper flange outside diameter; a lower flangehaving a central bore equal in diameter to said upper flange centralbore and oppositely disposed on the inner surface of said lower flange,a central counter-bore on an outer surface of said lower flangeconcentric with said lower flange central bore and oppositely disposedto said upper flange counter-bore and to which one end of said pipelineis welded, a lower flange annular tongue groove on said inside surfaceof said lower flange oppositely disposed from said annular upper flangetongue and mating therewith when said upper and lower flanges innersurfaces are held together, a lower fuze ribbon annular channel in saidlower flange inner surface oppositely disposed from said upper fuzeribbon channel and mating therewith;

means for holding said upper and lower flanges together;

a fuze detonating ribbon angularly contained in said upper and lowerfuze ribbon channels;

an O-ring located in said O ring groove contacts said lower flange innersurface and prevents said UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,780,753 Dated December 1973 Louis JablanskyInventor-(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet I73] Assignee: "The United States of America asrepresented by the Secretary of the Navy" should read The United Statesof America as represented by the Secretary of the Army signed'andfsealed this 3rd day of September 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner" ofPatents -'ORM PO-105O (10-69) v -gg 503764569 v w 0.5. GOVERNMENT nmmuoOFFICE I90 o-asu-asl,

1. A system for detecting an initial explosion in a pipeline carrying explosive materials and arresting said explosion prior to the propagation of a detonation wave along said pipeline which comprises: a breakwire sensor operatively positioned around said pipeline; an electronic switch having a pair of input terminals electrically connected to said breakwire for maintaining said electronic switch non-operative when said breakwire is intact, an a pair of output terminals for supplying a voltage pulse when said breakwire is broken, and which includes; a power source; a silicon controlled rectifier having an anode terminal connected to a positive terminal of said power source through a series connected charging resistor and switch, a trigger electrode connected to the common junction of a first terminal of said pair of input terminals and to one end of a voltage dividing resistor, said voltage dividing resistor having its other end connected to the common junction of said charging resistor and said anode terminal, a cathode terminal connected to a first terminal of said pair of output terminals; a load capacitor having one terminal connected to the common junction of a second terminal of said pair of input terminals and a second terminal of said output pair of terminals and the negative side of said power source, and a second terminal connected to the common junction of said anode terminal, said voltage dividing resistor, and said charging resistor,whereby said capacitor discharges its stored energy to said pair of output terminals when said breakwire sensor is broken, causing said silicon rectifier trigger electrode to be more positively biased, trIggering said silicon rectifier; and means for arresting a detonation disposed proximate said pipeline electrically coupled to said pair of output terminals and responsive to said voltage pulse which includes; an upper flange having a central counter-bore located on an outer surface of said flange to which said pipeline is welded, a second smaller central bore coaxial with said counter-bore and said pipeline connecting to an inner surface of said upper flange, an annular O-ring groove in said inner surface of larger diameter than said counter-bore and concentric thereto, an annular upper flange tongue larger in diameter than said Oring groove, concentric therewith and protruding from said inner surface, an upper fuze ribbon channel in said inner surface of larger diameter than said annular upper flange tongue and intermediate to said upper flange outside diameter; a lower flange having a central bore equal in diameter to said upper flange central bore and oppositely disposed on the inner surface of said lower flange, a central counter-bore on an outer surface of said lower flange concentric with said lower flange central bore and oppositely disposed to said upper flange counter-bore and to which one end of said pipeline is welded, a lower flange annular tongue groove on said inside surface of said lower flange oppositely disposed from said annular upper flange tongue and mating therewith when said upper and lower flanges inner surfaces are held together, a lower fuze ribbon annular channel in said lower flange inner surface oppositely disposed from said upper fuze ribbon channel and mating therewith; means for holding said upper and lower flanges together; a fuze detonating ribbon angularly contained in said upper and lower fuze ribbon channels; an O-ring located in said O ring groove contacts said lower flange inner surface and prevents said explosive material from escaping between said upper and lower flanges; an electrical detonator; and means for holding said electrical detonator in said upper and lower flanges so that said detonator is immediately adjacent to said fuze detonating ribbon, permitting said ribbon to explode when said electrical detonator receives said voltage pulse from said electronic switch, said ribbon explosion causing separation of said upper and lower flanges and separation of said pipeline sufficient to prevent propagation of the detonating wave along said pipeline. 